In a conventional imaging device such as a digital camera, a plurality of color processing parameters are stored within the image device in advance, one color processing parameter is selected from among these in accordance with the particular mode and image data obtained by imaging is subjected to color processing using the color processing parameter than conforms to the mode selected. The color processing parameter referred to here is data in a case where a condition (an output condition) that is to prevail at output of output data is specified for the input data by a program or the like.
In a conventional imaging device such as a digital camera, however, only the color processing parameters of modes that have been prepared beforehand can be set. In other words, color reproduction in line with user preferences cannot be realized in accordance with the image obtained by imaging.
Accordingly, the applicant has proposed a color processing parameter customizing apparatus [see the specification of Japanese Patent Application Laid-Open No. 2004-153684 (Patent Reference 1)] for the purpose of providing an apparatus in which the color reproduction of a digital camera can be set freely based upon user preference. The apparatus of Patent Reference 1 is adapted to find an optimum color processing parameter whereby photographic data obtained when a color chart that includes skin-tone color, the colors of sky and grass or the primary colors has been photographed by a digital camera is processed in such a manner that the original colors of the color chart or the skin-tone color and colors of sky and grass or colors such as the primary colors will approach a color (referred to as “target data” below) that the user deems to be desirable.
However, there is room for improvement with regard to the apparatus set forth in Patent Reference 1, as will be set forth below.
If the target data falls within the final target color space (e.g., sRGB, AdobeRGB, etc.), comparatively good color reproduction is obtained. However, if the target data is outside the target color space, there are instances where the image quality of color reproduction in the target color space will decline owing to the effect of the target that is outside the target color space. If the target data is outside the target color space, color reproduction of the target data per se cannot be achieved. Furthermore, if the target data is outside this color space, there are instances where the input data itself departs from the target (this is particularly true with regard to hue). If optimization is performed as is, data within this color space will also deviate together with the input data.
Thus, in a system in which a three-dimensional look-up table (3D LUT) is designed fully automatically, for example, it is difficult to realize good color reproduction.